1. Field
The present disclosure relates to a method for manufacturing a semiconductor device, and more particularly, to a method of manufacturing an ion injection mask.
2. Discussion of Related Art
A semiconductor device may include a memory cell array including a plurality of memory cells, a peripheral circuit configured to perform a program operation, a read operation, and an erase operation of the memory cells, and a control circuit configured to control the peripheral circuit.
Since the plurality of memory cells is included in the memory cell array, the memory cell array occupies a large area of the semiconductor device. In order to increase a data storage capacity of the semiconductor device, an area of the memory cell array is gradually increased. However, to suppress an increase in an area of the memory cell array and increase a data storage capacity, a memory cell array having a 3D structure has been developed.
The memory cell array having a 3D structure includes memory blocks having a 3D structure, and each of the memory blocks having the 3D structure includes strings having a 3D structure. The strings having the 3D structure include a plurality of memory cells stacked on a substrate in a vertical direction, and include a plurality of word lines connected to the memory cells, respectively, and stacked in the vertical direction.
AS described above, when the strings are formed in a 3D structure, heights of the strings are increased. When the heights of the strings are increased, it may be difficult to form a hole or a trench having a large depth during a manufacturing process.
Particularly, during an ion injection process for forming a junction in an ion injection target layer exposed at a lower side of the hole having a large depth, it is necessary to form ion injection mask patterns. However, foreign substances generated during a manufacturing process may not be completely removed and left at the lower portion of the deep hole. The foreign substances may cause a defective junction so that yield of the manufacturing process may deteriorate. As a result, reliability of the semiconductor device may also deteriorate.